Safety device



Mmmm/.0

H. A, MANTz SAFETY DEVICE Filed May 2o, 1940 Jane' 13, 1944.

Patented June 13, 1944 U N 1T E orales SAFETY DEVCE Application May 20,1940. Serial No. 336,090

(Cl. 15S-117.1)

8 Claims.

'I'his invention relates to safety devices for gas or other fuelburners.

Burners of this sort are subject at times to what is known in the art asa flash-back. In the case of a gas burner, for example, the gas isusually mixed with air in a mixing chamber adjacent the burner, and thecombustible mixture of gas and air is conducted to the burner where itis ignited by a pilot light. At times, the flame may flash back and thegas fuel burns in the chamber where the mixture of air and gas normallytakes place. Where such a flash-back occurs, the gas often burns withinsufficient oxygen, resulting in the production of a relatively largequantity of carbon monoxide, which is highly objectionable, and evendangerous, particularly in the absence ofy adequate flue connections.

One of the main objects of the present invention is to provide improvedmeans in combination with al gas or other fuel burner, which means willoperate automatically in the case of a flashback to shut off the supplyof fuel to the burner.

Another object of the invention is to provide improved means responsiveto thermal conditions in the mixing chamber or at the outlet from whichthe fuel for the main burner is delivered for controlling the supply offuel to the burner, and particularly for shutting off the supply of fuelto the burner in the event of an abnormal temperature at this location.

Another and more specific object of the invention is to provide incombination with a thermocouple placed in position to be heated by thepilot flame and connected to an electromagnet which is operative tomaintain a valve in the fuel supply pipe leadlng to the burner open aslong as the pilot flame is burning, a second thermocouple in position tobe exposed to heat resulting from a flash-back and arranged wholly orpar tially to counteract or neutralize the action of the firstthermocouple to release the valve for movement to closed position when aflash-back occurs.

Further objects and the features and advantages of the invention will beapparent from tion has been shown more or less schematically as embodiedin a manner automatically to close a valve in a fuel supply pipe leadingto a burner in case of a dash-back, and also when the pilot light forthe burner goes out.

Referring now to Figure 1 of the drawing, a gas or other fuel burner ofany suitable or preferred type is conventionally illustrated at I Theburner i0 may be the burner of a room or space heater, water heater,iloor furnace, range. or any other burner. A gas or other fuel supplypipe II leads to the burner i0 for the delivery -of gas or other fuelthereto-for example, through the outlet or delivery orifice i2 into themixing chamber i3 in which the fuel is mixed with air which enters themixing chamber through one or more ports M. The combustible mixture ofgas and air passes from the mixing chamber i3 through a conduit i5 tothe burner ill where it is delivered through the ports of the burner andignited by a pilot burner i6 in juxtaposition to the main burner.

The safety shuto valve I8 is incorporated in the fuel supply pipe Ii.The particular form of the valve i8 may vary widely within the scope ofthe present invention. The particular valve shown more or lessschematically in the drawing has an inlet i9 and an outlet 20 with avalve opening 2l for placing the inlet in communication with the outlet.A valve seat 22 is provided at one end of the valve opening 2l and, inthe illustrated embodiment of the invention, a second valve seat 23 isprovided at the opposite end of the valve opening. The pilot burner i6is shown as supplied with fuel by a pilot supply pipe 25 shown asconnected at 26 to the interior oi' the valve i8 between the valve seats22 and 23, it being understood that this may be varied within the scopeof the present invention.

The valve i8 is adapted to be closed by a valve member 2B to shut oilthe supply of fuel to the main burner and also, preferably, the supplyof fuel to the pilot burner as shown in the drawing. The electromagnet28 comprises a magnet frame 30 shown as of generally U-shaped form,although this may vary. The valve member 28 is connected by a stem 32 toan armature 33. When the armature 33'is placed in attracted positionagainst the pole ends of the magnet frame 3D and the electromagnetisenergized, as will presently appear, the electromagnet operates to holdthe armature 33 in attracted position and the valve member 28 open forthe supply of fuel to the main burner and also to the pilot burner i6.When the electromagnet 29 is deenergized, a

as will hereinafter appear.

spring, indicated at 38, actuates the valve member 28 to closed positionagainst the valve seat 22 to sh`-,ut off the supply of fuel to the mainburner and the pilot burner.

The electromagnet 28 has an energizing coil 36 which, in Figure 1, isshown as surrounding one of the legs of the magnet frame 38. This, ofcourse, may vary where the magnet frame is of other form, or where onlyone coil is provided, The energizing coil 36 is connected in circuitwith the thermooouple 38. 'I'he thermooouple 38 is placed in position sothat its thermojunction 38 will be heated by the pilot light when saidpilot light is burning. The construction of the thermooouple may besimilar to that disclosed in Oscar J. Leins Patent No. 2,126,564,granted August 9, 1938, or it may be of any other suitable-oi,`preferred form. One side of the energizing coil 36 is connected inoircuit with one of the thermooouple elements-for example, the outerthermooouple element 48- through a lead conductor 4I, and the other sideof the coil 36 is connected in circuit with the other thermoooupleelement, namely the internal thermooouple element 42 of the particularthermooouple shown, through a lead conductor 43.

The outlet member 45, having the outlet or orifice I2 through which thefuel enters the mixing chamber I3 and which is shown of tubular form andas mounted on the adjacent end of the fuel supply pipe II, constitutesone of the dissimilar metallic thermooouple elements of a secondthermooouple 48. The other metallic thermooouple element 41 of thethermooouple 48 is shown of annular form surrounding and spaced from theelement 45. The thermooouple elements 45 and 41 extend into the mixingchamber I3, and the innen end of the outer element 4l is contracted andjoined to the element 45 to form a thermojunotion 48. The thermojunction48 is thus disposed so that it-is responsive to thermal conditions ,inthe mixing chamber I3, or at the outlet I2, and, more particularly, sothat it will be heated by the flash-back name 58 which burns at theoutlet I2 in the case of a flash-back. Where there is no flash-backcondition, of course the flame indicated in dotted lines at 58 isabsent.- In the embodiment of the invention shown in Figure 1, theeleotromagnet 29 is shown as having a neutralizing coil 52 in additionto the energizing coil 36. The neutralizing coil 52 is shown assurrounding the other leg of the magnet frame 38 which, of course, mayvary where the magnet frame is of other form, or where only one coil isemployed. One side of the coil 52 is connected in circuit with thethermooouple element 45 through a lead conductor 54, and the other sideof the coil 52 is connected in circuit with the other thermoooupleelement 4'I through a lead conductor 55. y

The heat of the pilot light on the thermooouple 38 energizes theelectromagnet 28 sufolently to hold the armature 33 in attractedposition and the valve 28 open, assuming of course that there is noflash-back flame as indicated at 58, when the armature 33 is engagedwith the pole ends of the magnet frame, but this thermoelectrio currentis not capable of moving the armature to attracted position and thevalve member 28 to open position. Cooking means is therefore providedfor actuating the armature 33 to attracted position and the valve member28 to open position.

The cooking means comprises a cooking or reset stem 68 coaxial with thevalve member 28 and extending outwardly from the valve body. The outerend of the cooking stem 88 has a cooking or reset button 8| mountedthereon. The cooking stem 68 also has a flow interrupter disk 62 which,when the cooking stem 88 is pressed inwardly in the cooking operation,seats upon the valve seat 23 to shut off the supply of fuel to the mainburner. A ow interrupter disk spring is provided at 83, and upon seatingof the disk 82 upon the seat '23 in the cooking operation, the cookingstem is adapted to continue in its inward movement through the flowinterruptor disk to bring the armature 33 fully to attracted positionand the valve member 28 fully to open position. A spring 64 interposed,for example, between the valve housing and thercooking button 6I returnsthe cooking stem to its outwardly projected position upon completion ofthe cooking operation.

To start the operation of the system, the following sequenoe isfollowed:

The cooking stem 88 is pressed inwardly to aotuate the valve member 28to open position and the armature 33 to attracted position in contactwith the pole `faces of the magnet frame 38. This allows the fuel toflow through the pilot connection at 26 and pilot supply pipe 25 to thepilot burner I6 where the same is ignited.;A The stem 68 is held indepressed position until the pilot flame has heated the thermooouplesuiilciently to energize the eleotromagnet 28 so that it will hold thearmature 33 attracted thereto and, thereby, the valve member 28 in openposition. The flow interrupter disk 62 seats upon the valve seat 23 toshut off the flow of fuel to the main burner as long as the cooking stem68 is depressed.

When the eleotromagnet is energized sumciently to hold the armature 33in attracted position and the valve member 28 in open position, thelcooking stem 68 is released, thus allowing the flow interruptor disk 62to return to open or normal operating position. Fuel then flows outthrough the outlet 28 and fuel supply pipe II to the main burner whereit is ignited by the pilot burner I6. If the pilot burner is not lightedto produce the thermoeieotrlo current for holding the armature 33 inattracted position and the valve 28 open, the armature 33 will beactuated to retracted position and the valve member 28 to closedposition upon release of the cooking stem 68. Also if, after beinglighted, the pilot burner is extinguished, the armature 33 is releasedand the valve member 28 is actuated to closed position to shut oi thesupply of fuel to the main burner and to the pilot burner.

Upon normal operating conditions, the temperature of the thermojunotion48 is not high enough to set up the thermoelectrio current necessarysufiloienftly to neutralize the current set up .by the thermooouple 38,and the valve member 28 remains open as long as the pilot burner I8 islighted. However, in the event of a flash-back with the pilot lightburning, the flash-back flame, which then burns as indicated at 58,heats the i thermojunotion -48 and thereby sets up a thermoelectriccurrent in the neutri'ilizingl coil 52. This current neutralizes theholding effect of the ourrent in the energizing coil 36 sufficiently torelease the armature 33 and the valve member 28 is actuated to closedposition to shut off the supply of fuel to the main burner and the pilotburner. Upon discontinuance of the ash-baok condition. the neutralizingaction ceases to be effective, so that the system may be again set intooperation by pressing the -cocking stem l8|) and lighting the pilotburner, as already described. l

In the embodiment of the invention shown in Figure 2, the electromagnet28', instead of having an energizing coil and a neutralizing coil, has

only one coil 10 shown as wound around the legs of the magnet frame 30',it being understood that the coil 10 .may be otherwise arranged,particularly where the magnet frame is of a form other than that shown.

In this case, one side ci' the coil 10 is connected in circuit with oneof the thermoeouple elements 40', 42 of the thermccouple 38' by e. leadconductor 1I. The other element oi the thermocouple 38 is connected incircuit with one of the thermocouple elements 45', 4l of thethermocouple 48. The other element of the thermocouple 4'6 is connectedin circuit with theY other Y closed position.

Certain embodiments of the invention have been illustrated in theaccompanying drawing, but

it is to be expressly understood that said drawing is for purposes ofillustration only and is not to be construed as a deiinition oi thelimits or scope of the invention, reference being had to the appendedclaims for that purpose.

I claim:

1. In a flash-back safety device for gas burners, the combination with agas burner, a gas and air mixing chamber, a conduit for conveying thegas and air mixture from said mixing chamber to the burner, a tubularJet member constituting one of the elements oi' a thermoelectricgenerator and extending through a wall of said mixing chamber with itsinner end disposed within said mixing chamber and its outer end disposedoutside said chamber, a fuel supply pipe connected to the outer end ofsaid jet member for delivering gas into said mixing chamberl throughsaid jet member, a second thermocouple element extending through thewall of said mixing chamber .and joined inside said chamber to saidtubular iet member to form a thermoiunction adapted to be heated by aflash-bach iiame, and thermoelectric conductors connected to said firstand second mentioned thermocouple elements outside said mixing chamber.

2. In a flash-back safety device for gas burners, the combination with agas burner, a gas and air mixing chamber, a conduit for conveying thegas and air mixture from said mixing chamber to the burner, a tubularJet member constituting one of the elements of a thermoelectricgenerator and extending through a wall of said mixing chamber with itsinner end disposed within said mixing chamber and its outer end disposedoutside said chamber, a fuel supply pipe connected to the outer end ofsaid iet member for delivering gas chamber to said tubular Jet member toform thermojuncticn adapted to be heated by a dashback dame, andthermoelectric conductors -connected to said tlrst and second mentionedthermo couple elements outside said mixing chamber.

3. In a dash-back safety device for gas burners, the combination with amain gas burner, a pilot burner in juxtaposition to said main burner, agas and air mixing chamber, .a conduit i'or conveying the gas and airmixture from said mixing chamber to the main burner, a fuel supply pipeleading to said mixing chamber. a thermoelectric responsive valve insaid iuel supply pipe and comprising a magnet frame and a pairv ofoperating lwindings, a thermocouple in position to be heated by saidpilot burner and connected in circuit with one of said windings, and asecond thermocouple Y, having a thermoiunction disposed within saidmixing chamber and connected in circuit with the other winding toneutralize the action of said rst thermocouple when said secondthermocouple is heated by a dash-back llame in said mixing chamber.

4. In a device oi the class described, the combination of a burner, amixing chamber for mixing gas and air and supplying the mixture to saidburner, a gas supply pipe for supplying gas to said gas and air mixingchamber, a thermoelectric responsive control valve in said gas supplypipe comprising a magnet frame and a pair of operating windings, a pilotburner, a thermocouple in position to be heated by said pilot burner andconnected in circuit with one of said windings to maintain saidthermoelectric responsive control valve in open vposition as long assaid thermocouple is heated by the pilot burner, and a secondthermocouple connected in circuit with the other Winding and having ahot junction disposed within said mixing chamber, said secondthermocouple being normally deenergized and in position to be heated bya flash-back flame in the mixing chamber and adapted by energizing thewinding connected therewith to neutralize the action of said rstthermocouple for movement of said thermoelectric responsive valve toclosed position.

5. In a flash-back safety device for gas burners, the combination with amain gas burner, a pilot burner in `juxtaposition to said main burner, agas and air mixing chamber, a conduit for conveyng the gas and airmixture from said mixing chamber to the main burner, a fuel supply pipeleading to said mixing chamber, a thermoeiectric responsive valve insaid fuel supply pipe and into said mixing chamber through said ietmemcomprising an electromagnet, a thermocouple in position to be heatedby said pilot burner and connected in circuit with. said electromagnet,and a second thermocouple having a thermojunction disposed within saidmixing chamber and connected in circuit with said electromagnet toneutralize the action of said first thermocouple when said secondthermocouple is heated by a flashback flame in said mixing chamber.

6. In a fuel supply control system, a main burner, a fuel supply pipeconnected to said burner, an automatic shutoff valve yieldingly urgedclosed for controlling flow of fuel to said burner, a pilot burner,means comprising an armature attached to said shutoff valve, and anelectromagnet effective, when energized, for holding said shutoff valveopen, said electromagnet comprising a magnet frame and a pair ofwindings each independent of the other, a. thermoelectric generatoradapted to be heated by the flame of the pilot burner for energizing oneo! said windings of said electromagnet to hold said armature inattracted position and said shutoff valve open, and a secondthermoelectric generator disposed to be subjected to the heat of a ilameat the point of admission of fuel to said main burner, said secondthermoelectric generator beingconnected in circuit with the otherwinding independently of the thermoelectric circuit including said firstthermoelectric generator and acting, when heated by the latter ame, inopposition to said ilrst thermoelectric generator.

7. In combination, a gas burner comprising a gas and air mixing chamberhaving a wall provided with air inlet openings, a tubular jet memberconstituting one of the elements of a thermoelectric generator andextending through the wall of said chamber with its inner end disposedwithin said chamber and its outer end disposed outside said chamber, afuel supply pipe connected to the outer end of said jet member fordelivering gas into said chamber through said jet member, a secondtubular thermoelectric element surrounding said jet member and extendingthrough the Wall of said chamber with its inner end joined inside saidchamber to said tubular jet member to form a thermojunction adapted tobe heated by a ame in proximity to said jet member, an automatic shutoffvalve yieldingly urged closed controlling flow of fuel to said jetmember, an armature attached to said shutoff valve, and an electromagnetand energizing means therefor, said electromagnet being eiective, whenenergized, for holding said armature in attracted position and saidshutoi'! valve open, said electromagnet comprising a magnet frame and awinding on said magnet frame and connected in circuit with the tubularelements of the therm electric generator.

8. In combination, an electroresponsive device having an operatingposition and a safety position, said electroresponsive device comprisinga magnet frame, a first operating winding on said frame, a llameresponsive thermocouple connected in closed circuit relation with saidwinding and eiective when heated by a flame to maintain saidelectroresponsive device in one of said positions. Va second winding onsaid frame, and a normally deenergized thermocouple connected in closedcircuit relation with said second winding independently of said firstwinding and t0 neutralize the action of said rst thermocouple forenabling movement of said electroresponsive device to the other of itssaid positions when said second thermocouple is heated bya flame andthereby energized, the thermoelectric circuit including said ilrstwinding and said rst thermocouple being normally free, when said ilrstthermocouple is heated by a flame, of the resistance of said secondwinding and said second thermocouple, whereby for al given E. M. F.generated by the heat of a flame on said rst thermocouple the holdingaction of the .electromagnet is maximum.

' HAROLD A. MAN'IZ.

